Heat exchanger



M. H. KUHNER HEAT EXCHANGER Oct. 20, 1936.

2 sheets-sheet 1 Filed Jan. 27, 1936 A TEW 7 5 z 7 J: l l n n n n rLwlnJ-H ,6 B MIJ/6 z V LA; f /0 n 4 irl... w 3

OC. 20, 1936. M H.. KUHNER HEAT EXC HANGER Filed Jan. 27, 193e 2 sheets-Sheena C o 0 o o s 0000000000 gmc/who@ MAX H Kw1/'NEE Patented Oct. 20, 1936- y Y I UNITED STATES OFFICE HEAT EXCHANGERL Max H. Kuhner, Worcester, Mass.,. assignor to Riley Stoker Corporation, Worcester, Mass., acorporation 'of Massachusetts Application January 27, 1936, Serial No'.60,922

7 Claims. (Cl. 257-224) This invention relates to heat exchangers, and Fig. 3 is anenlarged'section on the 'line'f3'3 more particularly to apparatus of the type having of Fig. 1; a'bank of closely spaced parallel tubes through Fig. 4 is an enlarged section ontheline. l"-4 which a iluid is passed in heat transfer relation of Fig. 1; and

5 to -a second fluid outside of the tubes. Fg- 5 iS a freementary'perspectve viewofla l5 Heat exchangers of this type are frequently detail ofthe construction. used to preheat the air for combustion in boiler The -embodimentillustrated comprises aserles furnaces, the ainordinariiy traveling through 0f vertical tubes Ill arranged ir'r a rectangular the spaces between "the tubes, and the flue gases formationlA and with -their endSf"'elipanded iItO from the boiler traveling through the interior of Upper and IOWer horizontal tube'rsheets I I' and12 101 the tubes in countemow relation to the air. In respectively. A'hood l4fis'se'cured t0 thefupper such an air preheater it is important to avoid too tube sheet I I to form Ta' passage I5 with Vwhich great a cooling of the ilue gases Most fuels Y all the tubes connectrat` 'their 'uppers ends; 1 The A contain water, which is vaporized in the furnace. tubes are divided into two groups by a vertical Additional water -vapor is formed by the compartition I6 WhCheXten'dS' upwardly' from the-lei bustion 'of the hydrogen in the fuel. This water lower tube sheet l2 and terminates somewhat bevapor of course escapes from the boiler with the 10W the upper' tube Sheet II.' ThisV` PaTISI'fiOn" I5 ilue'gases, andvif the temperature of these gases is isi-Supported at the tOD by tie 10dSV "I8 extending lowered too much, water will condense and cause downwardly from a horizontal I-beam VI 9 mountcorrosion of the'tubes, usually near their dised above the upper tube sheet. A-gas inletlduct zi, charge ends Such corrosion may occur in cer- 2l)` connects with 'the' lower 'ends of the'tubes tain of'thetubes even though the temperature at One Side 0f the partiti0n,'and a gas outlet of the gases leaving the heater lis apparently duct 2I'connects withlthe lowerendsfof the tubes above the danger point. Applicant has discovered at the other side ofi-"the partition. The fgas lis that thisis caused by cooling the gases more in deliveredby the duct 20 land flows upwardly 25 certain--tubes-than in' others, usually because of throughthe corresponding tubes'to the passage ncn=unifdrxnf` distribution of the 'air throughout I5 and thence downwardly through'the remainthe spaces between the tubes. ing tubes to the'outlet -duct 2 I if It'I is accordingly one object of the invention to A second fluid',"such asair; is caused to-'flow .in

providef'a l`heat!exchanger :which will eiect a contact with the outer 'surfacesfof'` the tubes and 30 substantiallynnii'ornr transfer of heat from one n C0l1nte'r0w71elat0n 'Withthe feas# F01 this fluid `toanother.f purpose'the intermediate portions-'of the tubes It isla further object of the: invention to proare enclosed on all'fo'ur sideslby casing walls23; videa heatexchangerof the tubular type which The upper 'edges Of the'WellS 2312l1`e SDaGedbelOW .isso constructed and arrangedas to distribute the upper tube Sheet I I, and I31.11%"10We1' edges 0f 35 one of'the ilui'ds with substantial uniformity thesev Walls are spacedy above the lowerftube' sheet throughout the spaces between the tubes.l I2. A casing 24 connects the walls23 With'the Y It' is a further object of the invention to proupper tube sheet Il andy forms apassaget which videa heat exchanger of the tubulartype which surrounds the upper portions'of the tubes r`lllI on 40 will' be; simple and inexpensiveto manufacture, all four sides. An'air inlet ductv or ypassage 26 .40 and emcientin operation.l is provided to 'deliverair to theflower'portions With thesevand other objects in view, as will of the tubes adjacent to the` gas `outlet 2l; and bewapparent to those skilled in the artythe lnan air 'outlet' duct 01 passage' 2I'IS provided' t0 vention'resdesin the combination of parts set receive air fromzthe:lower'p0rf2i0l1e`0f IThe 'tubes vforth inftheuspecication vand covered :by the adjacent tothe gas inlet 201' AS' ShOWniIIFig'- 2, 45

claims appended hereto. the ducts 26and 2l jointly surround the tubes Referring tothe drawings illustrating Yonel emon all four sides." The air isl delivered` by: tthe bddiment of the invention, and'in whichV :like duct 2li and ilows'beneath the loweredge of 'the reference numerals indicate like parts, casing23 into the' spaces betweenl the tubes and :5,0 Fig. lis -a sectionalelevation of a heat exthence upwardly in contact'wththe outer'sur- 50 changer, the lower portinfbeing'fshown in secfaces ofthe tubes. Somev of' ther'air: then flows tion on-` thefline I"-I 'ofi Fig. .2; 'and the upper overtheupper edge ofthe partitionl vIii-,hand the Vportionbeing.shown'in'section on the: line Ia-I`a. remainder flows into the passage 25 and travels of1Fig.v2i i i through thiszpassagezan'd into the'spaces'between .f3.5 Fig. 2 is asection on'the line 2+-2 of Fig;1;..- thetubesat-theother'sidezotthe-partitiona The .55

other rows extend in diverging directions at angles of sixty degrees to the partition.

It is important to obtain substantially uniformV distribution of the air among the tubes. For this purpose the tubes are divided into groups which are separated by lanes 29 (Fig. 2) extending at right angles to the partition I6. The width of these lanes as shown is approximately equal to the diameter of the tubes. In the embodiment illustrated, lanes 29 divide the tubes into three' groups at each side of the partition. In each of these groups there is provided a pair of converging lanes 39 which extend inwardly from theouter margin of the group, opposite the partition I6, at angles of sixty degrees to the partition. These lanes may be formed by omitting tubes from certain of the diagonal rows. The lanes 29 and 30 form paths of decreased resistance which facilitate the flow of air into and out of the spaces between the tubes.

- With the construction as so far described, the air could flow laterally into the lanes 29 and 30, and then along these lanes in directions parallel to the tubes. This would decrease the efficiency of the heat transfer by allowing a considerable portion of the air to -escape intimate contact with the tubes. In order to prevent this, I pro-vide suitable baffles in the lanes. In the embodiment illustrated, I have shown a plurality of vertically spaced horizontal angle members 32 mounted in each lane 29, and a plurality of vertically spaced horizontal angle members 33 mounted in each lane 3U. As shown particularly in Figs. 3 and 4, the angle members are arranged with their concave faces upward on the side of the partition I6 where the air is flowing upwardly, and with their concave faces downward on the other side of the partition. The angle members 32 are supported at their-ends by the casing 23 and byv the'partition I6. The angle members33 are supported at one end by the casing 23 and at the other end by T-shaped columns 34 located at th-e intersection of each pair of lanes 30. Horizontal angle members 49 are secured to the opposite sides of the partition I6 to Vstiffen the same and to deflect the air away from the partition and into contact with the tubes.

The operation of the invention will now be apparent from the above disclosure. Hot flue gases are delivered to the inlet duct 26 and flow upwardly through the corresponding tubes I0 to the passage I5 and thence downwardly through thetubes on the other side of the partition I6 to the outlet duct 2|. Cold air is delivered to the inlet duct 26 and iiows laterally beneath the lower edge of the casing 23 and into the spaces between the tubes. Some of this air flows laterally through the lanes 29 and 30, and thus is able to reach the tubes near the partition I6, which are relatively remote from the air duct 26. In this manner a comparatively uniform distribution of the air is obtained among the lower portions of the tubes. 'Ihis air now fiows upwardly in contact with the tubes, andas it approaches the upper tube sheet Il a portion of the air flows overthe top of the partition I6 while the remainder ows laterally into the passage 25 and thus around into contact with the tubes on the other side of the partition. Ihe air thereupon iiows downwardly along the tubes, and as it approaches the lower tube sheet I2 it flows laterally beneath the lower edge of the casing 23 and into the outlet duct 21. The lanes 29 and 3D facilitate the entrance of the air into the spaces between the tubes and the exit of the air from these spaces. The bailies 32 and 33 prevent the air from traveling along these lanes in vertical directions. Heat is transferred through the walls of the tubes I0 from the flue gases inside the tubes to the air outside the tubes, and` since bo-th uids are substantially uniformly distributed with relation to the tubes the temperature of the gas leaving the various tubes is likewise uniform. It is therefore possible to reduce the gas temperature to a comparatively low value Without encountering abnormally low temperatures and resultant condensation and corrosion in certain of the tubes. The apparatus is simple and inexpensive to manufacture and efficient in operation.v

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A heat exchanger comprising a pair of spaced tube sheets, a group of tubes connecting said sheets, means to pass a uid through the interior of the tubes, an inlet passage located adjacent to one of the tube sheets and arranged to deliver a second fluid to the spaces between the tubes, the tubes being for the most part closely spaced but arranged to provide lanes of substantial width which communicate with the inlet passage and through which the second fluid may ow transversely of the tubes, walls enclosing the tubes and providing a passage through which the second fluid may flow longitudinally of the tubes, and baies located in said lanes to prevent flow along the lanes and longitudinally of the tubes.

2. A heat exchanger comprising a pair of spaced tube-sheets, a group of tubes connecting said sheets, means to pass a fluid through the interior of the tubes, an inlet passage located adjacent to one of the tube sheets and arranged to deliver a second iiuid to the spaces between the tubes, the tubes being for the most part closely spaced but arranged to provide lanes'of substantial width which communicate with the inletl passage and through which the second fluid may flow transversely of the tubes, walls enclosing the tubes and providing a passage through which the second uid may flow longitudinally of the tubes, and a series of baiiles located in each lane and spaced apart longitudinally of the tubes, said baflies preventing the second uid from flowing along the lanes and longitudinally of the tubes.

3. A heat exchanger comprising a pair of spaced tube sheets, a group of tubes connecting said sheets-and arranged in a plurality of rows in echelon formation, means to pass a fluid through the interior of the tubes, an inlet passage located adjacent to one of the tube sheets and arranged to deliver .a second fluid to the spaces between the tubes, tubes'being omitted in certain rows to provide lanes of substantial width which communicate with the inlet passageand through which the second fluid may flow transversely ofthe tubes, walls enclosing the tubes and providing avpassage through which the second fluid may owlongitudinallyfof the tubes, and baliles located in said lanes to prevent flow. along the lanes and longitudinally ofthe tubes.'

4. A heat exchanger comprising a pair of Vspaced tube sheets, a group of tubes connecting said sheets and arranged in a plurality of rows in echelon formation with each tube equidistant from six surrounding tubes, means to pass a fluid through the interior of the tubes, an inlet passage located adjacent to one of the tube sheets and arranged to deliver a second fluid to the spaces between the tubes, tubes being omitted in two non-parallel rows to provide two lanes of substantial width which communicate with the inlet passage and through which the second fluid may ow transversely of the tubes, walls enclosing the tubes and providing a passage through which the second fluid may flow longitudinally of the tubes, and baies located in said lanes to prevent ow along the lanes and longitudinally of the tubes.

5. A heat exchanger comprising a pair of spaced tube sheets, a group of tubes connecting said sheets and arranged in a plurality of rows in echelon formation, means to pass a fluid through the interior of the tubes, an inlet passage located adjacent to one of the tube sheets and arranged to deliver a second uid to the spaces between the tubes, tubes being omitted in two non-parallel rows to provide two intersecting lanesof substantial width which communicate with the inlet passage and through which the second fluid may flow transversely of the tubes, walls enclosing the tubes and providing a passage through which the second fluid may flow longitudinally of the tubes, members located at the intersection of the lanes and extending longitudinally of the tubes, and baffles located in the lanes and supported by said members, the baiiies being arranged to prevent flow along the lanes and longitudinally of the tubes.

6. A heat exchanger comprising a plurality of parallel tubes arranged in two groups, a partition located between the said groups, means to pass a fluid through the interior of the tubes, a casing surrounding the intermediate portions of the tubes, an inlet passage located adjacent to one end of one group of tubesand arranged to deliver a second iiuid to the spaces between the tubes, an outlet passage located adjacent to the corresponding end of the other group of tubes and arranged to receive the second uid from the spaces between the tubes, a passage located adjacent to the other ends of both groups of tubes to transfer the second fluid from the spaces between. the tubes of one group to the spaces'between the tubes of the other group, the tubes being for the most part f closely spaced but arranged to provide lanes of substantial width which communicate with said passages and through which the second uid may flow transversely of the tubes, and baflies located in said lanes to prevent iiow along the lanes and longitudinally of the tubes.

' '7. A heat exchanger comprising a plurality of parallel tubes arranged in twogroups, a partition located between the Lsaid groups, means to pass a fluid through the interior of the tubes of one group in one direction and thence through the interior of the tubes of the othergroup in the opposite direction, an inlet passage locatedadjacent to the discharge end of the second group and arranged to deliver a second iiuid to the spaces between the tubes, an outlet passage located adjacent to the inlet end of the rst group and arranged to receive the second iiuid from the spaces between the tubes, a passage located adjacent to the other ends of both groups of tubes to transfer the second iluid from the spaces between the tubes of theV second group tothe spaces between the tubes ofthe rst group, the tubes being for the most part closely spaced but arranged to provide lanes of substantial width which Ycommunicate with said passages and through which the second fluid mayv iiow transverseiy of the tubes, and bames mated in said lanes to prevent iiow along the lanes and longitudinally of the tubes.

MAX H. KUHNER. 

